► The production of bio-oil via the slow pyrolysis of dissolved air flotation (DAF) skimmings from poultry processing is described. The raw DAF skimmings were characterized…
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▼ The production of bio-oil via the slow pyrolysis of dissolved air flotation (DAF) skimmings from poultry processing is described. The raw DAF skimmings were characterized for physicochemical properties and for thermal behavior (TGA). The bio-oil was produced in a batch pyrolysis system at varying temperatures between 400 and 700 C to study the effect of temperature on product yield. The fatty acids in the bio-oil produced displayed a high degree of saturation that caused the bio-oil to have poor cold flow properties (high cloud point and viscosity) so a solvent extraction scheme was devised to extract a bio-oil fraction rich in unsaturated fatty acids that could be further esterified into a biodiesel and fatty nitriles that could be further processed into surfactants. This ethyl acetate-soluble fraction demonstrated much improved cold flow properties as well as lower water content and a higher HHV. The esterification of this soluble fraction was performed using methanol and sulfuric acid as an acid catalyst and the formation of fatty acid methyl esters was verified using GC/MS and FT-IR.
Advisors/Committee Members: K. C. Das.

►Pyrolysis is an energy production process involving the thermal decomposition of biomass in the absence of oxygen. Char, a byproduct of the pyrolysis process, has…
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▼Pyrolysis is an energy production process involving the thermal decomposition of
biomass in the absence of oxygen. Char, a byproduct of the pyrolysis process, has been suggested as a beneficial soil amendment. Instances of charcoal discovered in otherwise infertile soils have shown soil fertility improvements in highly weathered soils through an increase in cation exchange capacity (CEC), pH, and availability of nutrients such as N, P, Ca, and K. Several studies were conducted to determine if char from pyrolysis, produced at 400°C with steam from peanut hull and pine chip feedstocks, would provide similar benefits by improving plant growth, nutrient availability, soil moisture retention, and carbon sequestration. Overall, results show that char from peanut hull and pine chip feedstocks increase available nutrients, although this increase did not lead to significant increases in plant growth or yield. Amendment of pyrolysis char also increased soil moisture during dry greenhouse conditions. Studies of soil respiration and carbon mineralization indicate pyrolysis char resists decomposition and is stable in the soil profile.
Advisors/Committee Members: Lawrence A. Morris.

Speir, R. A. (2008). Use of pyrolysis char as an amendment in soils of the Southeastern United States. (Masters Thesis). University of Georgia. Retrieved from http://purl.galileo.usg.edu/uga_etd/speir_robert_a_200805_ms

Chicago Manual of Style (16th Edition):

Speir, Robert Adam. “Use of pyrolysis char as an amendment in soils of the Southeastern United States.” 2008. Masters Thesis, University of Georgia. Accessed June 07, 2020.
http://purl.galileo.usg.edu/uga_etd/speir_robert_a_200805_ms.

MLA Handbook (7th Edition):

Speir, Robert Adam. “Use of pyrolysis char as an amendment in soils of the Southeastern United States.” 2008. Web. 07 Jun 2020.

Vancouver:

Speir RA. Use of pyrolysis char as an amendment in soils of the Southeastern United States. [Internet] [Masters thesis]. University of Georgia; 2008. [cited 2020 Jun 07].
Available from: http://purl.galileo.usg.edu/uga_etd/speir_robert_a_200805_ms.

Council of Science Editors:

Speir RA. Use of pyrolysis char as an amendment in soils of the Southeastern United States. [Masters Thesis]. University of Georgia; 2008. Available from: http://purl.galileo.usg.edu/uga_etd/speir_robert_a_200805_ms

►Pyrolysis of biomass is the thermochemical conversion process whereby the long lignocellulosic polymers in biomass are cracked into several higher-value products such as bio-oil, bio-char…
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▼Pyrolysis of biomass is the thermochemical
conversion process whereby the long lignocellulosic
polymers in
biomass are cracked into several higher-value products such as
bio-oil, bio-char and
combustible non-condensable gases (NCG).
Fast pyrolysis in particular is aimed at maximising the
yield of
crude liquid bio-oil, with the production of bio-char and NCG as
co-products. Since a large
quantity of under-utilised biomass is
produced in the forestry sector annually, as by-product from
harvesting, this sector has shown particular interest in this
process. Furthermore, the continuing drive
for renewable and
sustainable energy production, particularly of drop-in liquid
biofuels, has urged the
development of such technology on a
commercial scale. The main purpose of this investigation was
to
evaluate the technical feasibility and performance of the scalable
dual fluidised bed (DFB) reactor
system designed and constructed
at the University of Pretoria by Swart in 2012. The sub-objectives
of this study were as follows:
• Biomass pre-treatment equipment
was implemented to ensure that the physical
characteristics of the
biomass feedstock meet the pyrolysis process requirements.
• The
scalable DFB reactor system, including all sub-systems and
ancillary equipment, was
commissioned to ensure satisfactory
operation of the complete system.
• Continuous, steady-state
experimental runs were conducted to produce fast pyrolysis
products in the scalable DFB reactor system.
• The fast pyrolysis
products were quantified and characterised to evaluate the
technical
feasibility of the DFB reactor system.
• A material and
energy balance was conducted over the pyrolysis fluidised bed (PFB)
reactor
to quantify its performance.
Eucalyptus grandis raw
material, as received from Sappi Southern Africa’s Ngodwana mill,
was
successfully converted to bio-oil, bio-char and NCG in the
scalable DFB reactor system. Fast
pyrolysis was conducted at a
pyrolysis temperature of 500 °C, a vapour residence time of 4 s and
a
sawdust feed rate of 2.0 kg/h. The PFB reactor temperature could
be controlled easily, at the desired
setpoint (500 °C), by
continuously circulating hot solids between the two bubbling
fluidised beds. The
excellent temperature control of the PFB
reactor makes the DFB system a suitable reactor system for
the
fast pyrolysis of biomass on a commercial scale. At these PFB
reactor conditions the yield of fast pyrolysis products, on a dry
feedstock basis, was
determined as 36.3, 14.0 and 49.7 weight %
for bio-oil, NCG and bio-char respectively. High-value
process
heat, in the form of hot flue gas (450–500 °C), was produced in the
combustion fluidised bed Although the crude liquid bio-oil
contained highly oxygenated compounds (including organic acids,
water, alcohols, esters, sugars, aldehydes, ketones, furans, pyrans
and phenolics) it may be utilised
for heat generation when
co-fired with conventional fossil fuels, including heavy furnace
oil. However,
the scalable DFB reactor system allows for
integrated catalytic fast…
Advisors/Committee Members: Heydenrych, Mike D. (advisor).

► One of the most promising technologies for net atmospheric carbon removal is biomass pyrolysis. Biomass pyrolysis is the thermal decomposition of organic material in the…
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▼ One of the most promising technologies for net atmospheric carbon removal is biomass pyrolysis. Biomass pyrolysis is the thermal decomposition of organic material in the absence of oxygen. It is generally endothermic but it results in high energy syngas, a liquid bio-oil and biochar, a carbonaceous material which when added to soil stimulates plant growth. Here, the economic potential of small-scale pyrolysis in the neo-tropical developing world is investigated using a net present value framework. Biomass costs are estimated using waste biomass, jaragua grass, short-rotation woody crops, and biomass from artificial wetland systems in Costa Rica. Costs are computed with and without consideration of the environmental services associated with the modeled systems. When environmental services are appropriately valued, the costs of biomass from artificial wetland systems becomes negative; that is, operators of artificial wetlands used for water services would be expected to pay for biomass harvesting. Using the computed biomass costs, pyrolysis system costs are computed for fast and slow pyrolysis and compared to gasification. Fast and slow pyrolysis systems break even at carbon credit prices exceeding 0-5 $/ton, but gasification systems do not break even under most realistic assumption sets. The emergetic costs of pyrolysis systems are also evaluated. Emergy is a measure of the energy and resources required to produce a product, and can be considered a theoretical alternative monetary or accounting system that allows for a more holistic valuation of goods and services than either an exchange (money) or value (exergy) system. The results indicate that the transformities (or emergetic efficiency) of pyrolysis production systems using waste biomass are similar or less than those of geochemical hydrocarbon production systems. Since geologic fossil fuel production is emergetically efficient, this result is promising and suggests that unlike other biomass based alternative energy systems (e.g. ethanol), pyrolysis may be ecologically beneficial when measured holistically. Pyrolysis is a carbon negative technology (i.e. it creates a long term carbon sink) which creates the potential for a cap and trade system in which there is differentiation between carbon neutral and carbon negative credits. The economics of such a system are discussed.
Advisors/Committee Members: Ronald Carroll.

Snyder, B. F. (2013). Ecological and economic costs and benefits of the use of pyrolysis as a climate change mitigation technique in the neotropical developing world. (Doctoral Dissertation). University of Georgia. Retrieved from http://purl.galileo.usg.edu/uga_etd/snyder_brian_f_201312_phd

Chicago Manual of Style (16th Edition):

Snyder, Brian Francis. “Ecological and economic costs and benefits of the use of pyrolysis as a climate change mitigation technique in the neotropical developing world.” 2013. Doctoral Dissertation, University of Georgia. Accessed June 07, 2020.
http://purl.galileo.usg.edu/uga_etd/snyder_brian_f_201312_phd.

MLA Handbook (7th Edition):

Snyder, Brian Francis. “Ecological and economic costs and benefits of the use of pyrolysis as a climate change mitigation technique in the neotropical developing world.” 2013. Web. 07 Jun 2020.

Vancouver:

Snyder BF. Ecological and economic costs and benefits of the use of pyrolysis as a climate change mitigation technique in the neotropical developing world. [Internet] [Doctoral dissertation]. University of Georgia; 2013. [cited 2020 Jun 07].
Available from: http://purl.galileo.usg.edu/uga_etd/snyder_brian_f_201312_phd.

Council of Science Editors:

Snyder BF. Ecological and economic costs and benefits of the use of pyrolysis as a climate change mitigation technique in the neotropical developing world. [Doctoral Dissertation]. University of Georgia; 2013. Available from: http://purl.galileo.usg.edu/uga_etd/snyder_brian_f_201312_phd

► Oil sands found in Athabasca and Cold Lake regions of Northern Alberta form Canada’s primary source of energy reserves. Asphaltenes, a significant part of bitumen…
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▼ Oil sands found in Athabasca and Cold Lake regions of
Northern Alberta form Canada’s primary source of energy reserves.
Asphaltenes, a significant part of bitumen is often considered to
be the least valuable component of crude oil due to various factors
such as difficulty in transporting and processing. However,
utilization of asphaltenes plays a crucial role in overall
economics of oil sands extraction. Gasification of asphaltenes can
result in much needed hydrogen for upgrading of bitumen. Pyrolysis
is the first step in gasification that directs formation of soot on
one hand and char formation on the other. However, very limited
study has been carried out on pyrolysis of asphaltenes in entrained
bed conditions. Single particle investigations are useful since
they are conducted in a well-controlled environment allowing
elimination of complexities arising from particle-particle
interactions. In this work, pyrolysis of pulverized Asphaltenes
feedstock was carried out in a drop tube furnace (DTF) maintained
in atmospheric pressure. Effect of furnace temperature and particle
size on char formation and char characteristics were investigated.
Chars obtained from higher particle size (1.7mm to 0.85mm) at
600˚C, 700˚C and 800˚C exhibited similar morphology to that of pure
asphaltenes while pyrolysis of particle sizes ranging from
250-425µm at higher temperatures (700-900˚C) demonstrated better
results with 10-2% volatile matter remaining in char. SEM as well
as cross sectional images of char particles indicated formation of
cenospheres and fragmentation of char particles at higher pyrolysis
temperatures. High pyrolysis temperatures also implicated loss of
active sites, increase in alkene content and aromatic condensation.
ICP MS investigation validated retention of K and Na along with
heavy elements such as V, Ni and Cu at temperatures above 700ᵒC.
Morphology of char obtained at different oxygen partial pressures
was also examined. Ultimately, the combustion reactivities of char
obtained at 700ᵒC, 800ᵒC and 900ᵒC for particle sizes 425µm-0.85mm,
355-425µm and 250-355µm were compared.

Pressure is one of the less studied parameters in respect to its effect on the pyrolysis of biomass.…
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▼

Research Doctorate - Doctor of Philosophy (PhD)

Pressure is one of the less studied parameters in respect to its effect on the pyrolysis of biomass. Most of the understanding of this effect is qualitative in nature. Very little insight has been reported in the literature, into the intrinsic physical and chemical processes governing the effect of pressure on the pyrolytic behaviour of biomass and its main structural components (cellulose, hemicellulose and lignin). The lack of a well scrutinised mechanistic model, able to account for the effect of pressure during biomass pyrolysis, reflects the present state of art in the field. This has hindered the development of suitable biomass thermal-converter unit operations functioning under optimised pressure, temperature and residence time, able to produce desirable products. These outputs may include the attainment of a specific phase partition (char, bio-oil and gases) and manipulation of the composition of these phases. Aiming to fill this important gap in knowledge, the primary objective of the present research was to investigate the effect of pressure and vapour-phase residence time on the pyrolysis characteristics of biomass. In pursuing this objective, we have designed and assembled a flexible fixed-bed high pressure experimental rig. Subsequently, we have deployed the rig to perform experiments on wood chips of biomass samples of eucalypt (Eucalyptus acmenoides) sapwood and heartwood, camphor (Cinnamomum camphora) heartwood, pine (Pine radiata) sapwood, and sugar cane bagasse (Saccharum officinanum). We have also undertaken experiments on commercial and experimentally extracted components of biomass (cellulose, hemicelluloses, and lignin). Our experiments comprised a thermal treatment which included a heating rate of 5 °C/min and Tmax of 450 °C, under an inert purge gas atmosphere of N2. We have executed parameterised experiments varying pressure (from 0.1 to 1.0 MPa) and vapour-phase residence time (0.6, 1.5, and 15 min). We have also carried out experiments on a high-pressure thermo-gravimetric apparatus, under operating conditions similar to those deployed in the experimental rig. The analytical instrumentation consisted of a micro gas chromatograph, allowing on-line analysis and quantification of the gaseous species, and a gas chromatograph-mass spectrometer to perform qualitative and quantitative analysis of the tarry fraction. Proximate and ultimate analyses of samples and pyrolysis products were performed using standard analytical techniques. From this set of experiments, we were able to demonstrate a dependence of product phase yields (char, tar and gases), their composition, and their quality on the structural composition of woody biomass. We have found that lignin contributes the most, and cellulose the least to the formation of char. We have also demonstrated that high pressures and long vapour-phase residence times act concomitantly to produce a high yield of char and gases, as a consequence of a reduction in the yield of tar. Cellulose responded to…

► Two one-dimensional numerical simulations were developed to model the pyrolysis of wood spheres, based on the proposed model developed by Park et al., 2010. Both…
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▼ Two one-dimensional numerical simulations were developed to model the pyrolysis of wood spheres, based on the proposed model developed by Park et al., 2010. Both of these models include physical processes coupled with a kinetic mechanism that describes the pyrolysis reactions, including heat transfer within the wood particle, chemical decomposition of wood into products, and the pressure-driven flow of gas-phase species through the porous media, described using Darcy's law. The Park model used the kinetic mechanism developed by Park et al., 2010, where wood decomposes through a few parallel reactions and secondary reactions to form gas, tar, and char. The Gauthier model implements a more detailed kinetic mechanism, presented by Gauthier et al., 2013, which describes the decomposition of the main constituents of wood - cellulose, hemicellulose, and three types of lignin - and characterizes gas and tar fractions with a limited number of components. To accurately determine the ability of the model to predict the pyrolysis process, both models were configured to match the experimental conditions presented in this thesis. This included an in depth study into the external heat transfer, material properties, and some kinetic parameters from the Park model used in the simulation. Model outputs were compared to thermogravimetric analysis mass loss profiles and time-resolved temperature and species profiles of permanent gases and several light volatiles from the slow pyrolysis of dry poplar wood spheres. Model predictions from both the Park and Gauthier kinetic mechanisms matched reasonably well with experimental data, although the Gauthier model predicted a very large production of species from the desorption of chemisorbed species at higher temperatures that was not seen experimentally. Additionally, both models were generally able to predict the trends in yields of species with particle size and temperature. From this study, the following were determined: (1) The main release of gaseous products occurred before the exothermic peak seen in the temperature profiles, which supports the view that this peak is caused by the decomposition of an intermediate solid. (2) Both the Park and Gauthier models predicted a higher yield for tar and a lower yield for char than seen experimentally, which could be caused by secondary char being formed from the decomposition of tar as it moves through the biomass particle. (3) Two peaks were observed in the species profiles for CH4 at low temperatures, supporting the notion of the release of chemisorbed species that is implemented in the Gauthier model; however, this release is much smaller than predicted by the model. The development of the Gauthier model contributes considerably to numerical modeling of the pyrolysis process. This model provides detailed information on the composition of volatiles being produced through the slow pyrolysis of thermally thick particles, as well as the timing of the release of specific species. While there are many advantages to using this model to predict…
Advisors/Committee Members: Datta, Ashim K (committeeMember).

► Anthropogenic climate change, caused primarily by excessive emissions of carbon dioxide, has led to a renewed interest in char, the solid product of pyrolysis. When…
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▼ Anthropogenic climate change, caused primarily by excessive emissions of carbon dioxide, has led to a renewed interest in char, the solid product of pyrolysis. When applied to soil as biochar it can both sequester carbon and improve soil function. To make its manufacture environmentally friendly and economically viable it is important to maximise char yield, which can be done by promoting secondary reactions.
This research shows that secondary reactions, which are enhanced by prolonged vapour-phase residence time and concentration, not only increase the char yield but are the source of the majority of the char formed. All four biomass constituents (extractives, cellulose, hemicellulose and lignin) undergo secondary reactions concurrent with primary reactions over the entire pyrolysis range ≈ 140 to 500 °C, which makes it practically impossible to separate them. Secondary char formation was confirmed to be exothermic which affects the overall heat of pyrolysis. Impregnating the feedstock with the elements K, Mg and P, which are plant macro-nutrients naturally present in biomass, resulted in the catalysis of secondary char formation. The results reveal that a first order reaction model does not describe pyrolysis accurately when char formation is enhanced by catalysis and secondary reactions.
Secondary char can be enhanced by increasing the particle size but there is a limit due to increased cracking and fracturing of the pyrolysing solid. This limitation is overcome by pyrolysis in an enclosed vessel, termed autogenous pressure pyrolysis, which was discovered to cause significant changes in the volatile pyrolysis products; indicating the co-production of a high quality liquid. This process, however, negatively affects the char properties relevant for biochar like the surface area, similar to self-charring and co-carbonisation of condensed volatile pyrolysis products. To increase research capabilities a unique high temperature/ high pressure reactor (600 °C at 20 MPa) was designed to allow the detailed characterisation of all three pyrolysis product classes under extreme pyrolysis conditions. This was demonstrated to be invaluable for understanding the underlying pyrolysis mechanism and physical processes at play.

Multielement ceramic powders in the Si/C/N system could be obtained by spray pyrolysis process. Synthesis parameters and their effect on powder chemical composition and morphology have been already studied. Nevertheless, the mechanisms of precursor decomposition and gas phase species recombination that take place in the reaction zone are still unknown. The aim of this study is the comprehension of the process, from the aerosol generation to the solid powders formation mechanisms. The shadowgraphy technique was used to characterize the spray, and coupled with the implementation of a numerical model of droplets transport and treatment through the device allowed to identify bimodal size distributions at the furnace entrance. This double approach let confirm the effect of physical and hydrodynamic phenomenon in drop size evolution. The introduction of a bimodal distribution into the pyrolysis furnace allows to consider a precursor decomposition mechanism in two steps, depending on the drop sizes. This hypothesis combined to the study of precursor decomposition at high temperature led to the proposal of powder formation mechanisms in which their chemical composition varies with the synthesis atmosphere.

▼ Briquettes containing 86-92% anthracite fines,
2.3-8.6% lignin, 4.5% silicon metal powder, and 0.9% hydrolyzed
collagen (gelatin) by mass have been investigated as a promising
coke replacement in the foundry industry. The inclusion of lignin
is important; we hypothesize it thermally fuses, providing the
necessary strength for the briquettes to maintain their structural
integrity throughout the extremely harsh pyrolitic conditions of
the foundry’s cupola furnace. In order to mimic the cupola
environment, eucalyptus hardwood lignin has been pyrolyzed at a
series of temperatures ranging from 300°C to 800°C for either 5,
10, or 20 minutes. Following pyrolysis the lignin samples were
subjected to nuclear magnetic resonance spectroscopy (NMR),
pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), X-ray
diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), and
Raman spectroscopy to gain insight into either the reaction
mechanism or the structure of the resultant lignin char. The
results of these techniques indicate that the content of aromatic
carbon within the lignin increases from 54.1% to 95.6% between the
control (un-pyrolyzed) lignin and the lignin pyrolyzed at 500°C for
20 minutes. The average distance between aromatic carbons and their
nearest hydrogen atom also increased, indicating the size of
aromatic domains is increasing. The XRD data indicate that while
the lignin has not become ordered and aromatic enough to be
considered “graphitic”, the order and crystallinity is increasing
and was trending in the direction of graphite. The diffraction
pattern of the 800°C sample roughly resembled the patterns of soots
and glassy carbon. Similarly, the Raman spectra of samples
pyrolyzed from 400°C to 800°C indicate that the lignin was becoming
more ordered; the disordered (D) and graphitic (G) peaks became
more defined within samples pyrolyzed at high temperature. The
samples did not reach a high level of graphitization but contained
ordered aromatic regimes.

► An increasing population growth and the improvements made to the lifestyles of developing countries are leading to an ever increasing need for energy of all…
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▼ An increasing population growth and the improvements
made to the lifestyles of developing countries are leading to an
ever increasing need for energy of all kinds. This increase in
energy demand will also lead to an increase in the emissions
generated by the current energy production methods. These facts
combined with the depletion of the world’s available fossil fuels
have led to a movement towards the increased use of renewable
energy sources. This work focuses on the conversion of both a
renewable fuel, Silver Maple sawdust, and a fossil fuel, Dietz
subbituminous coal, into gaseous fuel. It is important to utilize a
locally available biomass sample. Silver maple is a common woody
biomass readily available in the northeastern United States. This
study investigates the effects of co-utilization on the gaseous
products of the pyrolysis process. Pyrolysis is the thermal
decomposition of organic matter in an oxygen-free environment. The
objective of this study is to investigate the potential synergistic
effect of adding biomass to coal during pyrolysis on the gaseous
products. The objective was met by carrying out lab scale pyrolysis
experiments in an electrical tube furnace. The feedstock consisted
of 0%, 5%, 10%, 20% and 100% biomass. All feedstock blending
combinations were heated to 700˚ C and 900˚ C in order to observe
any effects of temperature on the synergistic effect of blending.
It was observed that higher biomass concentration increase the
quantity of syngas produced. The addition of this biomass species
to this coal did not have a synergistic effect on the gaseous
production of this process. While promoting hydrogen producing
reactions such as methane reforming all effects observed were
linear. There was no synergistic effect observed for the
co-pyrolyzing of silver maple sawdust and Dietz subbituminous
coal.

► This thesis examines two important physical phenomena that occur when solid fuels are exposed to external radiative heating: (1) the pyrolysis process in reaching ignition…
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▼ This thesis examines two important physical phenomena that occur when solid fuels are exposed to external radiative heating: (1) the pyrolysis process in reaching ignition conditions and (2) the natural convection around one or more radiatively heated fuel samples. A vegetation fire (bushfire, wildfire, or forest fire) preheating the vegetation which is in its path is a particular example which occurs in nature. However there are many more applications where modelling the pyrolysis process and/or the natural convection is of practical use. For the pyrolysis phenomena, a one-dimensional time dependent pyrolysis model is proposed. The mathematical model is solved numerically and results are used to analyse the influence of the size of a wood-based fuel sample, the heating rate it is exposed to, and its initial moisture content in the process of the sample reaching the conditions where it can produce enough pyrolysate vapour to support a flame (flash point). In many pyrolysis models in the open literature it is assumed that the fuel samples are dry. In the present study it is found that the initial moisture content has a marked effect for a fuel sample reaching its flash point. For the convection phenomena, a two-dimensional steady model, which explores the natural convection around one or more solid fuels, is also presented. The flame front is represented by a radiating panel. This means that the solid fuels receive a non-uniform heating rate depending on their geometry and location in relation to the panel. Changes in temperature and velocity profiles are monitored for varying heating rates and sample sizes (or, equivalently, the Rayleigh number Ra). Additionally, in the case of multiple fuel samples, changes in the distance between the fuels is also taken into account. For multiple fuels in arbitrary locations it is possible that one sample will block some of the radiation from the panel from reaching another sample. This means that the fuel sample will receive a reduced heating rate. This reduction in heating is also incorporated in the natural convection model. Both the pyrolysis and natural convection models are solved numerically using the finite element software package COMSOL Multiphysics. A comparison of COMSOL is performed with benchmark solutions provided by the open literature. A good agreement in the numerical results is observed.

► Plastics play an enormous role in modern manufacturing, but the extraction and refining of raw materials, followed by the synthesis of plastics themselves, represents an…
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▼ Plastics play an enormous role in modern manufacturing, but the extraction and refining of raw materials, followed by the synthesis of plastics themselves, represents an enormous energy investment into a product that is all too often simply “thrown away” into a landfill after a single use. Microwave-assisted pyrolysis is a recycling technique that allows the recovery of chemical value from plastic waste by breaking down polymers into useful smaller hydrocarbons using microwave heat in the absence of oxygen. This dissertation examines the use of a catalytic activated carbon bed in this procedure, using high density polyethylene (HDPE) as a model plastic. Initial tests with the batch input of HDPE produced a condensed pyrolysis oil comprising 35.5–45.3% aromatics, with the remainder primarily short-chain aliphatics. This oil was approximately three times lighter than that produced in the absence of catalyst, with a narrower range of molecular masses that matched those of the liquid transport fuels petrol and diesel (C5–C21). The non-condensable gases that resulted were short-chain aliphatics that could be used as feedstock for the creation of new chemicals (such as virgin HDPE), or fuels such as natural gas and LPG. The development of apparatus capable of adding sample in a continuous fashion enabled the processing of larger quantities of HDPE, and resulted in condensed products with a significantly higher aromatic content (>80% at 450°C), and which encompassed a somewhat narrower range of molecular masses compared with those produced in the batch mode; this was due to differences in kinetics and residence time that resulted from the different modes of sample introduction. As a result of processing larger quantities of HDPE it became apparent that the activated carbon deactivated over time, with a bed able to process around 3.5 times its mass in HDPE at 450°C before any significant changes in output products occurred. The decomposition of HDPE proceeds via thermal scission and radical-mediated mechanisms; high energy surface active sites facilitate the transfer of hydrogen and radicals, and this enhances overall cracking and lowers the activation energy for the formation of aromatics. Analysis of material deposited on the surface of the activated carbon confirmed that deactivation occurred through coking, with both cracking and deactivation thought to be enhanced by the formation of microwave-induced microplasmas. Overall, the microwave-assisted pyrolysis of HDPE using activated carbon produces a much narrower range of more valuable products compared with non-catalytic processing. While the process is not likely to be economic in its current form owing to the relatively rapid deactivation of the activated carbon, future configurations incorporating online reactivation may be able to economically provide a second use cycle for these materials, avoiding expending energy to extract and process increasingly scarce new raw material from the surface of the earth.

▼ <html> <head> <style> p {text-indent:20px;} </style> </head> <body> Future and current high-speed jet aircraft will require their fuels to act as the primary coolants as well as propellants. Fuels will be exposed to severe temperatures and pressures in hypersonic aircraft, up to 700°C and 130 atm, respectively, conditions that are supercritical for most pure hydrocarbons. Under supercritical conditions, hydrocarbon fuels undergo pyrolytic reactions, which may lead to the formation of polycyclic aromatic hydrocarbons (PAH), known precursors to carbonaceous solid deposits. Such deposits may clog fuel lines and injection nozzles, hindering safe engine performance. Hence, it is important to understand the reactions that lead to the formation of PAH. While jet fuels are composed primarily of alkanes, a significant portion of their composition is comprised of aromatics. In our effort to understand PAH formation, we must first understand the interactions of aliphatic and aromatic fuel components. Therefore, the aromatic model fuel toluene (critical temperature, 319°C; critical pressure, 41 atm) has been pyrolyzed both alone and in the presence of the aliphatic model fuel <i>n</i>-decane (critical temperature, 345°C; critical pressure, 20.8 atm) in an isothermal flow reactor at 570°C and 600°C, 94.6 atm, and 133 sec. Analyses of 12 gas-phase and 53 condensed-phase hydrocarbon products were performed with gas chromatography (GC) with flame-ionization detection (FID) and GC/FID coupled with mass spectrometry (MS), respectively. Results indicate that <i>n</i>-decane addition increases toluene conversion and product yields. In <i>n</i>-decane-doped toluene pyrolysis at 570°C, <i>n</i>-decane conversion is inhibited by the smaller radical pool relative to <i>n</i>-decane-only pyrolysis at the same temperature. 1-Alkene formation is generally enhanced compared to <i>n</i>-alkanes at 570°C, a result that contrasts with results obtained from <i>n</i>-decane-only pyrolysis at the same temperature. Additionally, results suggest that interactions of alkenes and benzylic-type radicals are important to the formation of high-ring number aromatics. Increasing the temperature to 600°C increases the conversions of both toluene and <i>n</i>-decane and causes a general rise in product yields. Yields of aliphatics and <i>n</i>-alkylbenzenes with long-carbon chains decrease at 600°C due to decomposition of the alkyl chain. Product yields as functions of <i>n</i>-decane concentration at 570°C and 600°C are presented, and possible product formation pathways are discussed. </body> </html>

Grubb, C. A. (2014). An experimental investigation of the effects of <i>n</i>-decane on the supercritical pyrolysis of toluene. (Masters Thesis). Louisiana State University. Retrieved from etd-04102014-231811 ; https://digitalcommons.lsu.edu/gradschool_theses/3819

Grubb CA. An experimental investigation of the effects of <i>n</i>-decane on the supercritical pyrolysis of toluene. [Masters Thesis]. Louisiana State University; 2014. Available from: etd-04102014-231811 ; https://digitalcommons.lsu.edu/gradschool_theses/3819

Montana State University

21.
Kan, George Lan-yuh.
A study of the thermal decomposition of 2-naphthyl disulfide.

► The rapid advance in information technology and the relentless desire of consumers for the “state of the art” products have led to an accelerated obsolescence…
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▼ The rapid advance in information technology and the relentless desire of consumers for the “state of the art” products have led to an accelerated obsolescence of e-waste. The majority of technologies that are being developed to re-process e-waste have concentrated primarily on the recovery of the metallic fractions. This has resulted in a growing concern in the generation of a tertiary waste in the form of plastic components of e-wastes. Thermochemical conversion, by pyrolysis of these plastic components offers a favourable method of converting the waste to generate easily transportable oil and chars. The key challenges in direct pyrolysis of e-waste plastics are the presence of brominated flame retardants and the subsequent formation of dioxins. Lowering the temperature of pyrolysis could suppress the formation of dioxin. The additional advantage of this would be the lowering of the energy requirement for pyrolysis.
Bioleaching offers a promising technology in extracting valuable metals from e-waste. Coupling this technology with pyrolysis based on our new technology, bio-hydropyrolysis, will offer a more complete solution to the management of e-waste. The microbial attack of plastics is known to induce chemical degradation as a result of bond cleavage. This study examined the potential of chemical/biodegradation of polymeric waste, achieved during the bioleaching process, to lower the temperature of pyrolysis. A series of experimental investigations was conducted using the six most common polymeric materials found in e-waste: High impact polystyrene (HIPS), Polypropylene (PP), Acrylonitrile butadiene styrene (ABS), Polyvinyl chloride (PVC), Polycarbonate (PC) and Flame Retardant Epoxy Resin (FR4). It is well known that these conventional plastics are not easily biodegraded under atmospheric conditions. Their biodegradability was therefore considered with the added use of heat and oxidizing reagents. The possibility of chemical depolymerisation was also considered.

► The hydropyrolysis of coal is considered to be an attractive future route for the conversion of coal to gaseous and liquid fuels and chemical feedstocks.…
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▼ The hydropyrolysis of coal is considered to be an attractive future route for the conversion of coal to gaseous and liquid fuels and chemical feedstocks. This thesis comprises a study of the behaviour of coal under the conditions pertinent to those envisaged within a commercial hydropyrolysis process, that is, using pulverised coal, a short coal-reactor residence time, high hydrogen pressure and high heating rate. For this purpose, an electrically heated grid apparatus has been used. The experimental conditions have been weighted towards achieving a maximum loss of primary volatile products whilst minimising unwanted and poorly controlled secondary reactions such as char hydrogasification. In this way, it has been possible to compare the influence of a hydrogen atmosphere on primary devolatilisation for a range of coals. Overall, the total volatile release is enhanced by hydropyrolysis to a degree dependent upon the partial pressure of the hydrogen. The increased yield is due mainly to an increase of saturated hydrocarbons, although the production of some individual species such as carbon monoxide, carbon dioxide and unsaturated hydrocarbons are diminished with respect to helium pyrolysis. The magnitude of both total and individual product yields vary with coal type, as does the degree by which these yields are influenced by a hydrogen atmosphere. This influence is considered to depend specifically on the type and number of various reactive sites and functionalities within coal and also on their accessibility for hydrogen, which is in tum dependent upon the thermoplastic behaviour of the coal. A further factor governing both product yields and hydrogen influence is the coal petrographic composition. Inertinite macerals have been observed to be significantly more responsive than exinite or vitrinite to hydrogen, producing relatively high methane yields. Thus it has been shown that inertinite rich coals or enriched feedstocks may be suitable candidates for hydropyrolysis processing. The data obtained have also demonstrated how a number of coal properties obtained by standard analytical techniques may be used for coal selection and yield prediction. BS volatile matter, carbon content, vitrinite reflectance and both 0/C and H/C atomic ratios are the most useful of the properties investigated in this respect. This is considered to be an important step towards the foundation of a classification system for hydropyrolysis processing.

Chlorella vulgaris was found as a good biosorbent
for copper, zinc and aluminum. pH value, reaction time, initial
metal and algal sorbents concentrations were considered as
parameters affecting metal removal efficiency. In appropriate
conditions, 85% of copper(II), 70% of zinc(II) and 99% of
aluminum(III) could be removed from solutions by tested microalgae
within 20 minutes. In following pyrolysis of the algae, metals were
further concentrated in the charcoal. 96.17% of Copper and 97.34%
of Zinc stayed in the char portion. Metals in the algal feedstock
improved the bioenergy production during microwave assisted
pyrolysis of the algae by reducing heating time to about half of
before. The presence of metals also significantly decreased the
nitrogen containing compounds and the carbon dioxide output and
increased the aromatics generation.

Zhao, Y. (2012). Heavy metals in wastewater: Their removal through algae
adsorption and their roles in microwave assisted pyrolysis of
algae. (Masters Thesis). University of Minnesota. Retrieved from http://purl.umn.edu/140181

Chicago Manual of Style (16th Edition):

Zhao, Yuan. “Heavy metals in wastewater: Their removal through algae
adsorption and their roles in microwave assisted pyrolysis of
algae.” 2012. Masters Thesis, University of Minnesota. Accessed June 07, 2020.
http://purl.umn.edu/140181.

Zhao Y. Heavy metals in wastewater: Their removal through algae
adsorption and their roles in microwave assisted pyrolysis of
algae. [Masters Thesis]. University of Minnesota; 2012. Available from: http://purl.umn.edu/140181

Texas A&M University

26.
Mukundan, Mallika.
Phase control in the synthesis of yttrium oxide nano and micro-particles by flame spray pyrolysis.

► The project synthesizes phase pure Yttria particles using flame spray pyrolysis, and to experimentally determines the effect of various process parameters like residence time, adiabatic…
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▼ The project synthesizes phase pure Yttria particles using flame spray pyrolysis, and to experimentally determines the effect of various process parameters like residence time, adiabatic flame temperature and precursor droplet size on the phase of Yttria particles generated. Further, through experimentation and based on the understanding of the process, conditions that produce pure monoclinic Y2O3 particles were found. An ultrasonic atomization set-up was used to introduce precursor droplets (aqueous solution of yttrium nitrate hex hydrate) into the flame. A hydrogen-oxygen diffusion flame was used to realize the high temperature aerosol synthesis. The particles were collected on filters and analyzed using X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). Individual process parameters (flame temperature, residence time, precursor concentration, precursor droplet size) were varied in continuous trials, keeping the rest of the parameters constant. The effect of the varied parameter on the phase of the product Yttria particles was then analyzed. Pre-flame heating was undertaken using a nozzle heater at variable power. Precursor solution concentrations of 0.026 mol/L, 0.26 mol/L, and 0.65 mol/L were used. Residence time was varied by means of burner diameter (9.5 mm and 1.6 mm ID). Large precursor droplets were removed by means of an inertial impactor. The higher flame temperatures and precursor heating favor the formation of monoclinic yttrium oxide. The fraction of the cubic phase is closely related to the particle diameter. All particles larger than a critical size were of the cubic phase. Phase pure monoclinic yttrium oxide particles were successfully synthesized. The end conditions included a precursor concentration of 0.65 mol/L, a pure hydrogen-oxygen flame and a 1.6 mm burner. The precursor droplets entrained fuel gas was passed through a round jet impactor and preheated at full power (130 VA). The particles synthesized were in the size range of 0.350 to 1.7 ?m.
Advisors/Committee Members: Guo, Bing (advisor), Annamalai, Kalyan (committee member), Collins, Don (committee member).

► Y2O3:Eu particles are phosphors that have found wide applications. Flamesynthesized Y2O3:Eu particles may have either the cubic or the monoclinic structure. The effects of particle…
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▼ Y2O3:Eu particles are phosphors that have found wide applications. Flamesynthesized
Y2O3:Eu particles may have either the cubic or the monoclinic structure. The
effects of particle size and Eu doping concentration on crystal structure and the surface
elemental composition of the flame-synthesized Y2O3:Eu particles had not been
previously reported.
In this study, a flame aerosol process was used to generate polydisperse Y2O3:Eu
particle. H2 was used as the fuel gas, with either air or O2 gas as the oxidizer. The
precursor was aqueous solutions of the metal nitrates, atomized using a 1.7-MHz
ultrasonic atomizer. The product particles were analyzed by transmission electron
microscopy (TEM), X-ray diffractometer (XRD), Selected area electron diffraction
(SAED), X-ray photoelectron spectroscopy (XPS), fluorescence spectrophotometer, and
inductively coupled plasma mass spectrometer (ICP-MS).
The Y2O3:Eu particles generated in H2/O2 flames were spherical and fully dense,
with diameters in the range of 10~3000 nm. In particle samples with lower Eu doping
concentrations, a critical particle diameter was found, whose value increased with increasing Eu doping concentration. Particles well below the critical diameter had the
monoclinic structure; those well above the critical diameter had the cubic structure. At
sufficiently high Eu doping concentrations, all Y2O3:Eu generated in H2/O2 flames had
the monoclinic structure. On the other hand, all particles generated in the H2/air flames
had the cubic structure. For the Y2O3:Eu particles generated in H2/O2 flames, XPS
results showed that the surface Eu concentration was several times higher than the
doping concentration. For Y2O3:Eu particles generated in H2/air flames, the surface Eu
concentration was equal to the doping concentration. For both types of particles, the
photoluminescence intensity reached a maximum corresponding to a surface Eu
concentration 40~50%. The photoluminescence intensity then decreased rapidly with
higher Eu doping concentration.
The effect of particle size and Eu doping concentration on crystal structure may
be explained by the interplay between surface energy and polymorphism. A mechanism
for this surface enrichment phenomenon was proposed based on the binary Eu2O3-Y2O3
phase diagram.
Advisors/Committee Members: Guo, Bing (advisor), Naugle, Donald G. (committee member), Zhang, Xinghang (committee member).

► The need for clean potable water and sustainable energy are two current and pressing issues with implications affecting the global population. Renewed interests in alternative…
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▼ The need for clean potable water and sustainable energy are two current and pressing issues with implications affecting the global population. Renewed interests in alternative energy have prompted researchers to investigate the full capacity of biofuels. These interests have led to not only the examination of current method limitations, but also to the investigation of new conversion methods. One promising method for bioenergy production is pyrolysis of lignocellulosic feedstocks. Through pyrolysis, a single crop may produce ethanol, bio-oil, and/or gaseous energy (syngas). The remaining solid phase product is a black carbon dubbed 'biochar'.
In the current study, biochar was used as a both an unamended sorbent and a precursor to form powdered activated carbons (PACs) capable of removing waterborne viruses. Biochar was activated with KOH, ZnCl2, and H3PO4 and analyzed using the Brunauer, Emmett and Teller (BET) method, a combination of Kjeldahl digest and ICP-MS, and scanning electron microscopy (SEM). Sorbents were tested in batch studies using phosphate buffered saline (PBS), surface water, and groundwater. Bacteriophages MS2 and thetaX174 served as viral surrogates.
All activation treatments significantly increased surface area, up to 1495.5 m2/g (KOH-activated). While the non-activated biochar was not effective in virus removal, the KOH-activated PAC had tremendous removal in the PBS/MS2 batch (mean 98.7% removal, up to 6.2 x 109 particles/mL, as compared to the Darco S-51: 82.3%).
As evidenced by this study, sorption efficiency will be governed by viral species, carbon type and concentration, and water quality. The results of this study indicate that biochar can serve as a precursor for a highly porous and effective PAC, capable of removing waterborne viruses from environmental waters.
Advisors/Committee Members: Gentry, Terry (advisor), Deng, Youjun (committee member), Pillai, Suresh (committee member).

► Thermal gasification of biomass is being considered as one of the most promising technologies for converting biomass into gaseous fuel. Here we present results of…
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▼ Thermal gasification of biomass is being considered as one of the most promising technologies for converting biomass into gaseous fuel. Here we present results of gasification, using an adiabatic bed gasifier with air, steam as gasification medium, of mesquite and juniper. From Thermo-gravimetric analyses the pre-exponential factor (B) and activation energy of fuels for pyrolysis were obtained using single reaction models (SRM) and parallel reaction model (PRM). The single reaction model including convention Arrhenius (SRM-CA) and maximum volatile release rate model (SRM-MVR). The parallel reaction model fits the experimental data very well, followed by MVR. The CA model the least accurate model. The activation energies obtained from PRM are around 161,000 kJ/kmol and 158,000 kJ/kmol for juniper and mesquite fuels, respectively. And, the activation energies obtained from MVR are around100,000 kJ/kmol and 85,000 kJ/kmol for juniper and mesquite fuels, respectively.
The effects of equivalence ratio (ER), particle size, and moisture content on the temperature profile, gas composition, tar yield, and higher heating value (HHV) were investigated. For air gasification, when moisture increased from 6% to 12% and ER decreased from 4.2 to 2.7, the mole composition of the dry product gas for mesquite varied as follow: 18-30% CO, 2-5% H2, 1-1.5% CH4, 0.4-0.6% C2H6, 52-64% N2, and 10-12% CO2.
The tar yield shows peak value (150 g/Nm3) with change in moisture content between 6-24%. The tar collected from the gasification process included light tar and heavy tar. The main composition of the light tar was moisture. The chemical properties of heavy tar were determined.
For air-steam gasification, H2 rich mixture gas was produced. The HHV of the mesquite gas increased first when S: F ratio increased from 0.15 to 0.3 and when the S: F ratio increased to 0.45, HHV of the gas decreased.
Mesquite was blended with the Wyoming Powder River Basin (PRB) coal with ratio of 90:10 and 80:20 in order to increase the Tpeak and HHV. It was found that the
Tpeak increased with the increase of PRB coal weight percentage (0% to 20%).
Advisors/Committee Members: Ansley, Jim (advisor), Annamalai, Kalyan (advisor), Petersen, Eric (committee member), Ranjan, Devesh (committee member).

Food security and hence access to environmentally sustainable food resources is one of the key global challenges in…
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▼

Research Doctorate - Doctor of Philosophy (PhD)

Food security and hence access to environmentally sustainable food resources is one of the key global challenges in the 21st century. In this context and from an agronomic perspective, the role of soil amendments (e.g. fertilisers) for enhanced food production cannot be overstated. One such soil amendment is biochar: a carbon-rich organic substance derived from biomass that has great potential to improve soil health by improving nutrient retention, particularly in coarsely textured soils. In addition, biochar can be used as a carbon sink and thus can be considered as an alternative means of reducing atmospheric carbon dioxide. Meanwhile, with the ever-increasing rates of coal production in Australia and around the world, management of mine waste, in particular coal tailings, is becoming a pressing issue. Given that both coal and biomass are organic substances with somewhat similar characteristics, the concept of ‘chailings’, a char created from coal tailings rather than biomass, for use as a soil amendment was proposed by our research team in 2009 and formed the basis of this thesis. As a result, the primary objectives of this thesis were to produce, characterise and apply chailings to soil and ultimately assess the concept for future work and scaled-up production. Chailings were produced via a slow pyrolysis process from tailings sourced from two coal mines (Mine A and Mine B) in New South Wales, Australia. Pyrolysis conditions were varied in terms of maximum heating temperature (400 °C to 850 °C) and holding time (0–6 hours) to create chailings with varying properties. Chailings were characterised using a number of techniques. X-ray diffraction and x-ray fluorescence techniques identified the primary mineral constituents as silica (i.e. quartz) and aluminosilicates (i.e. kaolinite or illite). Clear morphologic changes were observed via optical and scanning electron microscopy for increasing pyrolysis temperature, with evidence of particle swelling and devolatilisation apparent at high temperatures (>600°C). Proximate analyses indicated near complete devolatilisation was apparent at 800 °C for both mines, with thermogravimetric analysis revealing that peak devolatilisation occurred at 454 °C for Mine A and 464 °C for Mine B. Increases in pH and decreases in electrical conductivity (EC) and total acidic capacity were observed when pyrolysis temperature increased primarily due to the volatilisation of acidic compounds. A substantial increase in surface area with increasing pyrolysis temperature was observed for Mine A chailings, from 2.7 m²/g at 400 °C to 75.3 m²/g at 800 °C, because of the development of microporosity. However, a decrease was observed for Mine B chailings, from 2.4 m²/g at 400 °C to 1.2 m²/g at 800 °C, attributed to macroporosity and aggregation of particles. Overall, characterisation of chailings revealed that the physical and chemical properties of chailings were highly dependent on tailings sources and pyrolysis temperature, while holding time had…

Tremain, P. T. (2016). A fundamental study on char creation from coal tailings (‘chailings’) and its application as a soil amendment. (Doctoral Dissertation). University of Newcastle. Retrieved from http://hdl.handle.net/1959.13/1315128

Tremain PT. A fundamental study on char creation from coal tailings (‘chailings’) and its application as a soil amendment. [Internet] [Doctoral dissertation]. University of Newcastle; 2016. [cited 2020 Jun 07].
Available from: http://hdl.handle.net/1959.13/1315128.

Council of Science Editors:

Tremain PT. A fundamental study on char creation from coal tailings (‘chailings’) and its application as a soil amendment. [Doctoral Dissertation]. University of Newcastle; 2016. Available from: http://hdl.handle.net/1959.13/1315128